There are many applications where a plurality of sheets or planar type articles such as envelopes are to be conveyed to a stacking station and stored therein in inclined overlapped relation. In this type of operation there are three different types of variables that must be accommodated by the sheet conveying and stacking device if the latter is to have a wide range of application. First if the device is to be a stand-alone unit, its upstream end must be operationally adjustable to the extent necessary to cooperate with an adjacent upstream machine such as a postage meter, addressing machine, folding machine, etc. Secondly the device must be structurally and functionally capable of handling a wide range of sizes, shapes, weights, etc. of said planar type articles; and thirdly the device must be operationally flexible enough to allow the density and disposition of the stacked articles to be varied as desired or as required under many different sets of operating circumstances.
The known sheet stacking machines have for the most part fallen short of being able to accommodate all these variables and have tended to be relatively expensive and cumbersome.